66 



OTIORIIYXCHID^E. 



[Horn. 



Scrobes superior and convergent above. 

 Rostrum longer than the head, scrobes 

 very short terminal ; body with 



scales and setae THRICOLEPIS. 



Rostrum short ; scrobes nearly attaining 



the eyes ; body scaly only PERITELOPSIS. 



Scrobes more lateral not converging above. 



Scape as long (or very nearly so) as 



the funicle ; tibia? finely denticulate 



within GEODERCES. 



Scape much shorter than the funicle ; 



tibiae not denticulate ARAGNOMUS. 



Cotyloid surface of hind tibia? densely scaly. 

 Scrobes superior, slightly convergent 



above. 

 Eyes indistinctly surrounded by a 



groove. Scape feebly arcuate D YSTICHEUS. 



Scrobes lateral, not at all convergent. 



Orbital groove deep. 

 Scape arcuate and slightly twisted ; 

 scrobes lateral, deep, and attaining 



the eyes EUCYLLTJS. 



Scape straight or very feebly arcuate. 

 Scrobes very shallow posteriorly, not 



attaining the eyes THINOXENUS. 



Scrobes deep, attaining the eyes RHYPODES. 



The genera above indicated are so arranged as to exhibit a gradual transi- 

 tion from the Ptochoid forms of the preceding group to the TrachyphlOBoid 

 forms of the next. The rostrum tends to become shorter, also, as the 

 advance is made from the first to the last genus. The vestiture varies. 

 In one species Mylacus saccatus Lee., the surface is sparsely pubescent 

 without scales, Peritelopsis globiventris Lee., is scaly only without trace of 

 hairs or setae ; all the remaining species are densely scaly and with short 

 erect setae. As a general rule the nietasternal side pieces are extremely 

 narrow in the earlier genera (entirely concealed posteriorly in Mylacus} 

 and become more distinctly wider in the later genera, the suture, however, 

 is so very indistinct as to make it almost impossible to use the character 

 systematically. 



The scrobes vary greatly in form. In several genera they are plainly 

 superior and rather short, converging above. In others it is not easy to 

 determine whether to call them lateral or superior. When the scrobes are 

 much more distinctly open when viewed from above than when seen from 

 the sides they are called superior and conversely. None of our genera 

 show a lateral form of scrobe such as is seen in Omias or Lichenophagus. 



The occurrence of short fixed spurs to the hind tibiae in addition to the 



